1. Field of the Invention
This application is directed to a catheter pump for mechanical circulatory support of a heart.
2. Description of the Related Art
Heart disease is a major health problem that has high mortality rate. After a heart attack, only a small number of patients can be treated with medicines or other non-invasive treatment. However, a significant number of patients can recover from a heart attack or cardiogenic shock if provided with mechanical circulatory support.
In a conventional approach, a blood pump having a fixed cross-section is surgically inserted between the left ventricle and the aortic arch to assist the pumping function of the heart. Other known applications involve providing for pumping venous blood from the right ventricle to the pulmonary artery for support of the right side of the heart. The object of the surgically inserted pump is to reduce the load on the heart muscle for a period of time, to stabilize the patient prior to heart transplant or for continuing support. Surgical insertion, however, can cause additional serious stresses in heart failure patients.
Percutaneous insertion of a left ventricular assist device (“LVAD”), a right ventricular assist device (“RVAD”) or in some cases a system for both sides of the heart (sometimes called biVAD) therefore is desired. Conventional fixed cross-section ventricular assist devices designed to provide near full heart flow rate are too large to be advanced percutaneously, e.g., through the femoral artery.
There is a continuing need for improved cannula that provide sufficient expansion force and a stable expanded shape while still allowing for reliable and easy collapse to a delivery size. In other words, the cannula should have sufficient force to expand, but also be collapsible under significant sheathing force while avoiding a risk of damaging the cannula during re-sheathing. There is a continuing need for improved cannula that can be expanded and collapsed, in some cases over many cycles, without risking breakage of the struts and connectors forming the mesh. Broken struts pose a risk of complicating patient treatment and/or compromising the performance of the device.